private $stop;
 
        /**
-        * @var boolean
+        * @var bool
         */
        private $premium;
 
                $this->locked = null;
                $this->created = new \DateTime('now');
                $this->updated = new \DateTime('now');
+               $this->application = null;
                $this->applications = new ArrayCollection();
        }
 
        /**
         * Set premium
         *
-        * @param boolean $premium
+        * @param bool $premium
         *
         * @return Session
         */
         *
         * @return Session
         */
-       public function setApplication(Application $application): Session {
+       public function setApplication(?Application $application): Session {
                $this->application = $application;
 
                return $this;